This invention relates to misfire detecting apparatus for an internal combustion engine.
The internal combustion engine having a catalytic converter in the exhaust system has the serious drawback that the engine misfires on account of, for example, poor condition of the ignition device or the fuel system. The result is that the unburnt mixture emitted from the engine advances into the catalytic converter, which leads to the thermal failure of the converter due to enormous amounts of heat arising in a reaction therein. In order to avoid this draw back, an overheat preventing device for the catalytic converter must be actuated by detecting misfire of the internal combustion engine to check the catalytic converter from overheating.